Preparation of tetrahalomethanes



United States Patent Office 3,182,092 Patented May 4, 1955 3,182,092 7PREPARATION OF TETRAHALGMETHANEEE Robert Neville Haszeldine, Disley,England, and Hyman Iserson, Springfield Township, Montgomery County,Pa., assignors to Pennsalt Chemicals Corporation, Philadelphia, Pa., acorporation of Pennsylvania No Drawing. Filed May 21, 1959, Ser. No.814,683 Claims priority, application Great Britain, Oct. 12, 1955,29,117/55 4 Claims. (Cl. 260-653) This invention pertains to an improvedmethod for the preparation of tetrahalomethanes, particularly ofchlorofluoromethanes. This application is a continuation-inpart ofapplication Serial No. 606,542, filed August 25,

with a fluorocarb-onyl compound having the general formula where X isselected from the group consisting of fluorine, chlorine and bromine andY is selected from the group consisting of chlorine and bromine.

The method of the invention is of particular impor- E tance as appliedto the formation of halogenated methanes of the type Cl Cl.,

where n is from 1 to 3.

Reactions typical of the present invention are:

Similarly, when COFY is heated alone, the direct disproportionation ofCOFY into the tetrahalornethanes and CO (e.gi, Equations 2 and 4 above)can be accompanied by the setting up of equilibria of the type withsubsequent reactions of the COF and COY as indicated in Equations 1, 3,5, 6, 7, above.

The following equilibria are also of importance:

it it In Reactions 1 and 3 the COF may be formed in situ by the reactionbetween COY and HF, as follows:

The COF thus formed then reacts with the COY as indicated above. Thus,the overall reaction may be written:

The invention therefore also includes a method of making bromoandchlorolluorornethanes by reacting compounds of the general formula COYwith HF.

Similarly, in Reaction 1, the phosgene may be replaced by CO and C1which react according to the equation:

to form phosgene in situ. The phosgene then reacts with COF asindicated. Thus, the overall reaction may be Written:

The invention therefore includes a process for makingfluorochloromethanes by reacting carbonyl fluoride with carbon monoxideand chlorine.

From Reactions 12 and 14 it can be seen that chlorofluoromethanes can bemade from carbon monoxide, hydnogen fluoride and chlorine, in accordancewith the equation:

The invention therefore further includes a process for makingchlorofiuoromethanes by reacting hydrogen fluoride with chlorine andcarbon monoxide.

Although Reactions 12, 14 and 15 have been shown as yielding only CF Clit will be understood that the other tetrahalomethanes referred to abovemay also be present in the reaction products and, under certainconditions, may be present in greater proportions than CF Cl Theproportions of the various compounds obtained in the product will dependon the conditions of reactions, and on the type of catalyst used, asdescribed in more detail below.

The novel processes can be carried out under flow or batch conditions attemperatures between about 250 C. and about 1400 C. When a flow processis used, the temperature is preferably between about 400 C. and about800 C. Under batch conditions, the temperature i usually between about300 C. and about 700 C., preferably between about 350 C. and about 500C. With either process, and especially when HP is a reactant, thereaction can be carried out advantageously at temperatures below 550 C.

Pressure is not a critical consideration and the reactions may beperformed at atmospheric pressure. However, elevated pressure, such aspressures up to about 7500 p.s.i.g. or even higher, are preferred asincreasing the yield. Preferably pressures between about 700 and 4500p.s.i.g. Will be used.

When the reaction involves two different carbonyl halides, the moleratio of the two carbonyl halides will, in general, be within the rangefrom 10:1 to 1:10; usually, however, the two carbonyl halides will beused in approximately stoichiometric proportions although in certaincases it may be expedient to use an excess of one carbonyl halide, forexample as in Reactions 1, 3 and 12, when an excess of phosgene orcarbonyl bromide may be employecl, say between about 1 and about 10times the stoichiometric equivalent.

The reaction time required is simply that necessary to produceeconomical yields. It may vary from a few seconds in the case of a flowprocess to on the order of 24 hours for a batch process.

As pointed out, the reactions may be performed with or without acatalyst. However, use of a catalyst increases the reaction rate to aconsiderable extent. The catalyst of choice is activated carbon. Inusing a carbon catalyst, it is preferable to remove residual amounts ofash, volatile matter and water which may be present in commercialproducts and which will react with phosgene, fiuorophosgene,chlorofiuorophosgene or hydrogen fluoride. Commercially availableactivated carbon can be made suitable for catalysis of the presentreactions by treating it with anhydrous HF and then placing it undervacuum of say 0.1 to 10 mm. Hg at an elevated temperature (e.g., ZOO-400C.) for from say A to 10 hours.

The yield of halomethanes can be increased to some extent byimpregnating the purified carbon with the halide of a transitionelement, such as iron, vanadium, cobalt, a

or nickel, or with aluminum halide. Examples of suitable halides oftransition elements are ferric chloride, ferric fluoride, and mixturesthereof. The use of such materials, however, under certain conditionstends to promote Reactions 8, 9, and 10 to form CF CI, CFCl CBr F, CFBr, CBr CF and CC].,.

In Reactions 1, 3, 5 and 12, it may be desirable to add a small amount,say from about 0.1 to about 3 moles per mole of COCl or COBr of chlorineor bromine to the reactants to suppress dissociation of the phosgene orbromophosgene according to the reactions:

Similarly, if it is desired to suppress Reactions 8, 9 and 10, as whenCF Y is the desired product, the disproportionation products CF Y, CF CYF, and CY; may be added to the reactor along with the primary reactants.

The invention is further described in the accompanying specificexamples. It will be understood that these examples are given forpurposes of illustration only, and are not to be taken as in any wayrestricting the invention beyond the scope of the appended claims.

Example I The procedure of Example I was carried out using 0.1 mole ofCOF and 0.1 mole of COCI The temperature ranged from 320 C. to 370 C.over a period of 2.2 hours. The exit gases were condensed in trapscooled with liquid oxygen, then washed through 15% aqueous potassiumhydroxide. Spectroscopic analysis of the washed gases showed them to be(mole percents) CF CI 50%, COCl 10%, CO 40%, and a little CF 4 ExampleIII A carbon tube, 30 long, 0.75" I.D., 0.37" wall thickness, was usedas the reaction chamber. It was filled with activated carbon pelletswhich had been used in an earlier run and inserted in a nickel tube; theannular space between the tubes was filled with powdered graphite andfitted with graphite asbestos packing at each end. The two ends of thenickel tube were fitted with caps which were connected to A" tubingwhich served as the inlet and outlet tubes. A Monel thermowell, equippedwith thermocouples, was welded to the outside of the nickel tube. Thetube was heated in a 36 tube furnace.

0.24 mole COF and 0.66 mole COCl were released from small cylinders intoa mixing vessel from which they passed into the inlet tube of thereactor over a period of six hours. The temperature of the reactor was665 C. at its hottest point. The gaseous products, collected in liquidoxygen-cooled traps, were examined by infra-red spectroscopy whichshowed them to consist of (mole percents) 5-10% CO 50% COCI 510% COFl020% COFCl, 10% SiF and 10% chlorofiuoromethanes. It was then washedthrough 15% aqueous KOH. Infrared analysis of the gases which passedthrough the KOH showed them to be (mole percents) 40% CF Cl 20% CF Cl,and 40% CF.,.

Example IV The procedure of Example III was carried out using 0.07 moleof COF and 0. 1 mole of COCI The temperature ranged from 660 C. to 690C. over a period of 0.5 hour. 6% conversion of CF CI and CF CI wasobtained.

Example V About 35 g. activated carbon of the type used in Example I wasplaced in an 0.11 stainless steel autoclave which was then charged undervacuum with 0.36 mole COF and 0.42 mole C001 The autoclave was thenheated at 435 C. for 14.5 hours after which it was cooled to roomtemperature and vented to traps cooled in liquid oxygen. An infraredanalysis of the gaseous product showed about 10% CO 20% COF 20% COCl 25%COFCl and 25% chlorofiuoromethanes. This gas was washed with 15 aqueouscaustic and the gas which passed through the alkali was again examinedby infrared and found to contain (mole percents) 35% CF Cl 43% C F Cland OF Example VI A 0.3 liter stainless steel autoclave was charged withg. activated carbon and 10 ml. anhydrous HF were added. The autoclavewas placed in a heated shaker, heated at 225 for one hour and thenevacuated while still hot for 0.75 hour. 1.43 mole C001 and 0.2 mole COFwere added under vacuum and the bomb was then heated for 8 hours in afused salt bath at 425 C. At this temperature the pressure wascalculated to be about 7275 p.s.i.g. The bomb was cooled to roomtemperature, vented to liquid oxygen-cooled traps until it was atatmospheric pressure, and then heated to 250 C. in vacuo. An appreciableamount of liquid remained in the trap after it had been allowed to reachroom temperature. The liquid was removed, washed with 2% Na CO dried anddistilled to give 21 g. 1B.P. 7477 (3., n 1.4570, identifiedspectroscopically as carbon tetrachloride. 2.2 g. of crude C Cl remainedin the stillpot.

An infrared spectrum of the product which had volatilized when theproduct trap had been allowed to reach room temperature showed CF Cl CFC1, CF COCl and CCl This material was washed with aqueous KOH and theunabsorbed gases were found to consist of 50% CF CI 25 CF Cl, 10% CFCl8% CR 5% C01 and 2% COCl The conversions to chlorofiuoromethanes were45% CF CI 2 2.5% CF CI, 9% CFCI and 7.5% CR a total of 84% CF Cl ExampleVII The procedure of Example VI was carried out using 0.3 mole C001 and0.11 mole COF 110 grams of catalyst were used. The temperature was 425C. and the time of reaction was 17.5 hours. The observed pressure was1425 p.s.i.g. The gaseous product contained (mole percents) 50% CF CI60% CF Cl, 5% C FCl and 15% 6E Example VIII A :1 liter stainless steelautoclave was charged with 63 g. activated carbon catalyst which hadbeen used in an earlier experiment and which had been impregnated withferric chloride so that the percentage of ferric chloride in thecatalyst mass was 26-27%. 0.33 mole COCI 0.13 mole COF and 3 g. C1 werethen introduced under vacuum, and the bomb was heated in a fused saltbath at 425 C. for six hours. At this temperature the pressure wascalculated to be about 6310 p.s.i.g. The products were removed asdescribed in Example VI and were washed through 25% aqueousKOl-I. Aninfrared spectrum of a portion of the product which did not react withthe alkali showed the presence of 40% CF CI 25% OF Ol, 30% OFCl CFtraces of COCl and C0 The conversions to chlorofluoromethanes were 34%CF Cl 21% OF Cl, 25% CFCl and 4.5% CR or a total of 84.5% CF Cl About 3g. OCl were also obtained.

Example IX 80.5 g. COFCl (90-95% pure, 0.34 mole) were distilled undervacuum into a 0.1 liter stainless steel autoclave which was then heatedin a fused salt bath at 420 C. for 8.5 hours. The autoclave was ventedas described in Example VI. -An infrared spectrum of the crude productshowed approximately 45% C001 30% COF-Cl, 5% COF OFgCl -i-OF Cl, and 50%C0 The crude gas was washed through 15% aqueous KOH, introduced into avacuum system, and a sample was taken for an infrared analysis. Thespectrum showed (mole percents) less than 5% =COCl a trace of CH, 65-00%CF CI and 30% OFgCl.

Example X A 0.1 liter stainless steel autoclave was charged with 60 g.activated carbon which has been impregnated with ferric chloride so thatthe amount of ferric chloride in the catalyst was 262:7%. Thirty-ninegrams anhydrous hydrogen fluoride were added to the autoclave which wasthen heated at 300 and then evacuated. It was then cooled in a liquidoxygen bath and 30 g. COFCl (85% pure, 0.31 mole) were introduced undervacuo. The bomb was heated in a fused salt bath at 425 for 19 hours, ata calculated pressure of about 3565 p.s.i.g., cooled, and vented,finally with evacuation to liquid oxygen-cooled traps. An infraredspectrum of the exit gas showed the presence of C001 COFCl, CFgCl, CF ClCOF CCl and CO This crude product was washed twice with 25 aqueous KOHand the washed gas was found to contain CF2 60% OF Cl and 20% *CF CI Theconversions, calculated on the basis that one mole of COFCl yields onemole of chlorofiuoromethanes were: 12.5% CF Cl 37.5% CF Cl and 12.5% CFExample XI One hundred and two grams of activated carbon pellets whichhad been impregnated with 26-27% by weight of ferric chloride wereplaced in a 0.3 liter Monel bomb. The catalyst was pretreated with 27 g.HF and the bomb was evacuated at 275 C. The autoclave was cooled inliquid oxygen and 60 g. COCl 12.5 g. anhydrous HF and 7.5 g. chlorinewere introduced under vacuum. The ves sel was heated at 425 C. for 17hours at a calculated pressure of 4720 p.s.i.g., cooled, and vented to atrain consisting of sodium thiosulfate solution, aqueous KOI-I andliquid oxygen-cooled traps until it was at atmospheric pressure. Ventingwas completed by heating the bomb to 275 while evacuating it through aliquid oxygen-cooled trap. An infrared spectrum of a representativesample of the aqueous alkali washed product showed 75% CFgCl, 5% CF Cl5% CR; and a trace of phosgene. The conversions were 13.5% CF Cl 53.5%CFgCl and 3.5% CF or a total of 70.5% CF Cl Example XII One hundred andtwenty grams of FeCI -impregnated carbon which had been used in severalprevious reactions of COF and C001 were used as the catalyst. The bomb Vwas evacuated, charged with 60 g. C001 12 g. anhydrous HF and 7 g.chlorine, and heated for 6 hours at 350 C. and 4070 p.s.i.g.(calculated) in a fused salt bath. It was then cooled and vented througha sodium fluoride packed tube to a liquid oxygen-cooled trap until itwas at atmospheric pressure. The bomb was then heated to 250 C. andevacuated through a trap cooled in liquid air. The weight of crudeproduct was 69.5 g. This material was washed through aqueous sodiumthiosulfate and 25% aqueous KOI-I to give 22.5 g. of washed product.About 6 g. of the crude did not volatilize into the wash solutions andthis material was found to be mostly carbon tetrachloride. An infraredanalysis of the washed gases showed that they contained about 70% CF CI20% CF Cl, 10% CFC1 and a trace of CF The conversions were therefore 45to CF CI 13% to CF Cl, 7% to CFCl or a total of 67% CF Cl Example XIIIThe procedure of Example XII was carried out using 0.25 mole each ofCOCl and anhydrous HF and 0.05 mole of C1 grams of activated carbonimpregnated with FeCl which had been used for two previous runs wereused as catalyst. The temperature was 345 C. and the reaction time was6.25 hours. The observed pressure was 850 p.s.i.g. Conversions based onCOCl were 22% to CF Cl 17% to CF CI, 2.5% to CFCl and 2% to Example XIVThe procedure of Example XII was carried out using 0.5 mole COCI 0.45mole HF (anhydrous) and 0.1 mole C1 100 grams of activated carbonimpregnated with FeCl used in a previous run were used as catalyst. Thetemperature was 340 C. and reaction time was 6.25 hours. The observedpressure was 2000 p.s.i.g. Conversions based on C001 were 33.5% to CF Cl20%, to CF Cl, 10% to CFCl and 3.5% to CF Example XV One hundred gramsactivated carbon pellets were placed in a 300 ml. nickel autoclave, 30g. anhydrous HF was added and the autoclave was heated at 350 C. for 1.5hours while it was evacuated. It was then cooled in liquid nitrogen and152 g. CF Cl was introduced under ,vacuum. The bomb was put into astirred, fused salt bath which was kept at 350 C. for six hours. Themaximum pressure (observed) was 2925 p.s.i.g. The autoclave was removed,cooled, vented, and a sample of the exit gas was taken for infraredspectroscopic analysis. From the analytical data, it was calculated thatthere was present 6.1 g. CF Cl, 10.1 g. CFCl and 132.8 g. CF Cl ExampleXVI One hundred grams of catalyst were prepared as described in ExampleXV. One hundred and fifty-two -g. of CF Cl were introduced and thereaction was run as in Example XV except that the maximum pressure(observed) was about 3350 p.s.i.g. Venting of the autoclave yielded 128g. of material of which 13 g. was nonvolatile. Analysis of infraredspectroscopy technique showed that there had been removed from theautoclave 79.6 g.

'7 CF CI 17.3 g. CF Cl, 18 g. CFCI 15.8 g. CCL; and some CF We claim: 1.A method for making tetrahalomethanes which comprises reacting acarbonyl halide having the general formula Where X is selected from thegroup consisting of fluorine, chlorine and bromine and Y is selectedfrom the group consisting of chlorine and bromine, with a fluorocarbonylcompound having the general formula the halide of a transition element,at a temperature of between about 250 C. and 1400 C.

3. A method for making fluorochloromethanes which comprises reactingphosgene with carbonyl fluoride at a temperature of between about 250 C.and 1400 C., said phosgene being formed in situ by reacting carbonmonoxide and chlorine.

4. A method for making fluorochloromethanes which comprises pyrolyzingCOFCl in the presence of an activated carbon catalyst containing thehalide of a transition element, at a temperature of between about 250 C.and 1400 C.

References Cited by the Examiner UNITED STATES PATENTS 2,709,189 5/55Farlow et al. 260-653 2,757,213 7/56 Coffman et al. 260653.7 2,757,2147/56 Muetterties 260653.8 2,836,622 5/58 Tullock 260-6537 OTHERREFERENCES Ruif et al.: Z. Anorg. Chem. 242 (1939), pp.2726.

LEON ZITVER, Primary Examiner.

ALLAN M. BOETTCHER, ALPHONSO D. SULLL VAN, Examiners.

1. A METHOD FOR MAKING TETRAHALOMETHANES WHICH COMPRISES REACTING ACARBONYL HALIDE HAVING THE GENERAL FORMULA